The Biological Stain Commission (BSC) is an organization that provides third-party testing and certification of dyes and a few other compounds that are used to enhance contrast in specimens examined in biological and medical laboratories. The BSC is a 95-year-old organization well known to many thousands of scientists, worldwide but especially in N America, who buy BSC-certified stains for staining microscopic preparations and for making selective culture media for bacteria. Manufacturers and other vendors submit samples from their batches of dyes to the BSC's independent laboratory in Rochester NY. The BSC's certification label on a bottle of dye indicates that the contents are from a batch that passed the tests for chemical purity and for efficacy as a biological stain. These tests are published (Penney et al. 2002a). Changes to tests and additions to the list of stains eligible for certification are published from time to time in Biotechnic & Histochemistry and are summarized on the commission's web site. The BSC is a non-profit organization, incorporated in the State of New York, for the purpose of ensuring a supply of high quality stains (mostly dyes) for use in biological and medical laboratories. Its origins date from 1922, when vendors of biological stains in the USA had exhausted their stocks of pre-war dyes imported from Germany. American dye manufacturers were unable to produce products that were consistently reliable in histological microtechnique and bacteriology (Conn 1980–1981; Penney 2000). The commission's testing laboratory was initially at the Agriculture Experimental Station in Geneva, NY, directed by Harold J. Conn. Since 1947 the laboratory has been located at the University of Rochester Medical College, Rochester, NY. Currently 57 individual dyes and about 5 mixtures of different dyes are eligible for testing and certification by the BSC. The assays and other tests used in the commission's laboratory are all published, making the required standards known to both vendors and users of biological stains (Penney et al. 2002a,b). The commission's web site includes instructions for submitting samples of stains for testing and certification. Since 1925 the BSC has published a scientific journal, named Stain Technology until 1991, when the name was changed to Biotechnic & Histochemistry. Biological Stains, a book about the chemistry, testing and applications of dyes and other colorants in biology and medicine, has been published by the BSC since 1925. The first seven editions (1925-1961) were by H. J. Conn. The eighth and ninth